Air return filter grilles are comprised of a plenum which may be sheet metal or fiberglass, attached to a metal frame mounted in ceilings, walls, and sometimes mounted on T-bar ceilings. The frames are constructed usually of aluminum or sheet metal with a perforated face plate or grate hingedly attached on one side, closed and held in place by screws on the side opposite the hinge. The sheet metal frame has a cavity or recess for mounting a filter behind the face plate. Besides being quite heavy in construction, the replacement of the filters require special tools for releasing the screws holding the face plate in position. Another disadvantage is that the substantial metal construction can make them noisy when air is flowing through the return filter. Also the cost, weight and bulk of metal construction are additional substantial disadvantages.
It is therefore one object of the present invention to provide an air return filter mounting grille substantially lightweight in construction.
Yet another object of the present invention is to provide a air return filter grille, having a unique molded fiberglass plenum with foil reinforcement.
Yet another object of the present invention is to provide a lightweight air return filter grille, having high acoustical absorption, surpassing the substantial steel or metal units presently in use.
Still another object of the present invention is to provide air return filter grille which makes it easy to change the filter without the need for special tools or equipment.
Yet another object of the present invention is to provide an air return filter grille having an unique fiberglass construction with the perforated face plate attached by a hinge directly to the molded fiberglass to provide a substantial reduction in weight and allow easy mounting on T-bar ceilings.
Still another object is to construct an air return filter grille which mounts flush in T-bar suspended ceilings and matches in appearance air supply units. The unique construction provides a clean uncluttered design without the usual metal frame around the perforated metal face.